Continuous casting plants of this type are used, for example, for producing large so-called beam-blank formats with a double-T profile of over 800 mm length, over 400 mm width of flange and approximately 120 mm web thickness. The dummy bar head is also used, as is known in the art, to seal off the mould underneath before and during the casting start-up process.
During casting, the molten mass is poured through a pouring spout and channel into the interior cavity of the mould where it solidifies until it can be drawn off with the dummy bar head as a hot bar. To compensate for the shrinkage of the bar in the mould which occurs during the solidification process, the mould forms a conicity by running slightly at an angle from the top down. Since large beam-blank formats are cast more slowly than smaller formats, they require a relatively large conicity in the mould. For this reason, the entrance to the mould for such formats is about 6-12 mm larger than the exit.
Before starting casting, the dummy bar head with the associated packing is mounted above the mould and then inserted into the mould until it has reached the position for start of casting therein. Since the packing in systems of prior art is rigid, due to the conicity of the mould, a gap forms there at the inner shoulder of the profile. In the case of large formats, the gap is unacceptably wide. It is especially important in the casting start-up position, however, for the dummy bar packing to have a perfect seal, in order to prevent molten mass flowing out of the interior of the mould during casting. State of the art systems are therefore unsuitable for casting especially large-format profiles.